1. Field of the Invention
The present invention relates to a yield enhancing agent which increases the yield of a harvesting part of crop.
2. Background Art
Methods for enhancing the yield of crops include a method of treating with triacontanol during a tillering stage of rice (Chemical regulation of plants, 28 (1), 79, (1993)), a method of subjecting seeds of beans to an immersion treatment in carpropamide (JP-A-2001-247417), and the like.
However, the yield enhancing techniques as described above require restriction or management of the amount of practical use in consideration of the chemical characteristics of the active ingredients, or strict establishment of the conditions for actual use or combined use with other components upon stably increasing the yield of crops.
On the other hand, 5-aminolevulic acid, derivatives thereof, or salts of the acid or the derivatives exhibit an enhancement of photosynthetic activity, an enhancement of CO2 absorption capacity, a respiratory suppressing action, a chlorophyll content increasing action, and an excellent growth promoting action. As a result, the compounds are known to be excellent in the effects of promotion of rooting, prevention of falling down, enhancement of yield, enhancement of cold resistance, retainment of freshness, enhancement of green color, maintenance of green color, retainment of good seedling, growth promotion of organs, increase of tillering number, reduction of the time required for growth, alleviation of harmful effects of chemicals, and enhancement of survival in cuttage or the like (JP-A-4-338305).
Furthermore, it is reported that when sugar beet seedlings are treated with uniconazole P, which is an inhibitor of gibberellin biosynthesis, and then treated with 5-aminolevulic acid, a derivative thereof or a salt thereof, healthy growth of sugar beet seedlings can be carried out (Proceedings of Japanese Society for Chemical Regulation of Plants, No. 38, p. 71). This is a technology in which the problem that the effect of uniconazole P used to prevent turion in sugar beet seedlings is sustained so that growth stagnation such as reduction of the dry weight occurs, is solved by treating with 5-aminolevulic acid after 15 days of uniconazole P treatment, and thereby increasing the dry weight with the growth promoting effect of 5-aminolevulic acid, so as to return to healthy growth.